package com;

import java.util.HashSet;
import java.util.Set;

public class Demo03 {

    public static void main(String[] args) {
        HashSet<String> hst = new HashSet<>();
        hst.add("1");
        hst.add("2");
        boolean contains = hst.contains("2");
        System.out.println(contains
        );

        System.out.println(hst);


        boolean b=true;
        String s = String.valueOf(b);
        System.out.println(s);
        int length = s.getBytes().length;
        System.out.println(length);

        StringBuilder sb = new StringBuilder();

    }
}
